Etching machine



J. R. HARRIS ETCHING MACHINE June 4 1963 Filed March 19, 1959GSheets-Sheet 1 mmvron JEROME E. HAP/PAS Va? Arm/wa s J. R. HARRISETCHING MACHINE June 4, 1963 Filed March 19, 1959 6 Sheets-Sheet 2FIG.3.

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ETCHING MACHINE Filed March 19, 1959 e Sheets-Sheet 4 If/ZM- FIG. Ila.El Z/fl "l 2 A ol AA1 A1 C- /102 0 214 AA M51, I

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IN V EN TOR.

JEROME 1Q. HARE l5 AMJD J. R. HARRIS ETCHING MACHINE June 4, 1963 FiledMarch 19, 1959 A. M 2 5P I. w i. 0% e II I- m I. S I I. 6

S E s F H H in I M m H Id v 1 H I m. NH J T G a 14 A I 7 El m III June 3J. R. HARRIS 3,09

ETCHING MACHINE Filed March 19, 1959 6 Sheets-Sheet 6 INVENTOR. x/EIPOMER. HA'QQ/S mww i k/ 1,

HTVORNEYS The present invention relates generally to etching apparatus,and in particular to an automatic etching machine suitable for thepreparation of rotogravure printing cylinders and the like.

In the preparation of rotogravure printing cylinders, it is the usualpractise after placing the resist onto the cylinder surface to rotatablymount the cylinder over an etching stand with provision for turning thecylinder on its axis. An etcher then proceeds with the use of etchingacids of various Baume's to etch the cylinder to the degree required tocomplete the cylinder for printing. The etcher uses the acids of variousBaums in different sequences and in varying amounts and times toobtainthe requisite surface properties to enable proper reproductionwhen the cylinders are used for printing. Such etching procedures, apartfrom being very time-consuming, requires the use of exceptionallyskilled and trained personnel. Even with very highly skilled etchers,there often is substantial variation from cylinder; and it is difiicultto reliably reproduce substantially the same quality of printed materialalthough successive printing cylinders may be prepared from theidentical copy.

Broadly, it is an object of the present invention to provide anapparatus for etching which obviates one or more of the aforesaiddifficulties. Specifically, it is within the contemplation of thepresent invention to provide improved equipment making possible thesubstantial automatic etching of printing cylinders with the facilityfor maintaining and reproducing quality from cylinder to cylinder.

conventionally, the resist for the printing cylinder used in the gravureprocess has been prepared with carbon tissues. The use of carbon tissueimposes certain practical limitations in the rotogravure process due tothe inherent instability of the materials of the carbon tissues. Usingessentially the same process and the same carbon tissue, it is difficultto reliably reproduce printing cylinders time after time, which inconjunction with the highly discretionary etching procedures which havebeen followed, has made it unfeasible to even attempt to establish asemi-automatic or automatic procedure for etching printing cylinders.However, in recent times, there has been introduced a new type ofgravure etching resist which has found widespread application as asubstitute for the well known carbon tissue used in the production ofprinting plates and cylinders for printing presses. Such gravure etchingresist includes an emulsion layer of a fine grain presensitizedorthochromatic gelatin, a stripping membrane in the form of a thin filmwhich serves as a Waterproof protective layer during successive laydownsof resist on the printing cylinders and is removed by a solvent prior tohot-water development, a film base support, and an antihalation backingwhich serves to counteract curling of the film. Such resist is usuallyexposed with low wattage incandescent lights and suitable filters tocontrol contrast or density range. It has been found that with the useof such photographic gravure etching resist it is possible to prepareprinted and photographic matter with the assurance of excellentreproduction over the entire tone scale. Thus there has been realized asa first step toward standardization of the preparation of rotogravureprinting cylinders, the initial preparation of,

the photographic gravure resist which may then be developed and appliedto the printing cylinder. Details of atent ice improved equipment forautomatic developing such photographic gravure etching resists are foundin my copending application Serial No. 767,865, filed October 17, 1958,and entitled Photographic Processing Equipment.

I have found that with appropriate standardization of the initialpreparation of the printing cylinder, primarily the application of thephotographic gravure resist thereto, it is possible to reliably etchprinting cylinders with out the need of processing with as many as fourand five acids. In particular, with control over ambient conditions andstandardization in the preparation of the resist-covered printingcylinder, it is possible to etch printing cylinders using only twoacids, with the printing cylinder being exposed in accordance with themethod and apparatus aspects of my invention.

In accordance with an illustrative embodiment demonstrating features andadvantages of the present invention, there is provided a machine foretching printing cylinders which comprises a frame, carrier means on theframe adapted to engage and support the printing cylinder, an etchingtrough including first and second side by side wells, lateral guidemeans engaging and mounting the trough on the frame for side to sidemovement with the first well normally being disposed below the printingcylinder, means operatively connected to the carrier means for movingthe carrier means vertically to lower and raise the printing cylinderrelative to the wells such that the printing cylinder may be subjectedto the action of the action of the etchants in the first and secondwells, and means operatively connected to the trough for moving thetrough horizontally to shift the second well to a position belowtheprinting cylinder. Advantageously, my machine includes a control forcoordinating the movement of the carrier means and the trough such thatthe first printing cylinder is lowered into the first well, raised fromthe first well and after shifting of the trough to position the secondwell below the printing cylinder, lowered into such second well.

In accordance with further apparatus aspects of the invention provisionis made for rotatively supporting the printing cylinder, with a driveoperatively connected to the printing cylinder for rotating the printingcylinder on its axis. After a first phase of the etching cycle, thedrive is reversed to turn the printing cylinder in the oppositedirection with a view to compensating for any irregularities in etchingswhich might occur incident to continuous rotation of the printingcylinder in one direction throughout the etching cycle.

The above brief description, as well as further objects, features andadvantages of the present invention will be more fully appreciated byreference to the following detailed description of presently preferred,but illustrative etching machine demonstrating apparatus of the presentinvention, when taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a front elevation view of an etching machine demonstratingfeatures and aspects of the present invention;

FIG. 2 is an end elevational view of the machine, taken from the rightof FIG. 1;

FIG. 3 is a fragmentary sectional view taken along the line 33 of FIG.1, looking in the direction of the arrows, with part broken away andwith the wash boom omitted in the instance of simplicity;

FIG. 4 is an enlarged fragmentary transverse section of a portion of theetching trough showing details of an illustrative air-bubbling systemfor agitating the etchants in the respective wells of the trough;

FIG. 5 is a sectional view taken substantially along the line 55 of FIG.1, shown with the printing cylinder lowered into the No. 1 etchingsolution or acid;

FIGS. 6 to 10 inclusive are successive diagrammatic showing of therelationship between the printing cylinder and the etching trough duringsuccessive portions of a typical etching cycle wherein;

FIG. 6 shows the printing cylinder in position for movement of acylinder truck onto run-up rails, with the final loaded position of theprinting cylinder being shown by the dot dash lines; FIG. 7 shows theprinting cylinder in its raised pos1- tion loaded on the carrier member,with the trough laterally shifted to a forward position wherein the No.1 etching solution is positioned below the printing cylinder forexposure thereto;

FIG. 8 shows the immersion of the printing cylinder in the No. l etchingsolution;

FIG. 9 shows a time later in the cycle after the printing cylinder hasbeen raised out of the No. l etching solution and the trough laterallyshifted to a position wherein the No. 2 etching solution is beneath theprinting cylinder with the printing cylinder being shown lowered intothe No. 2 etching solution;

FIG. 10 is a diagrammatic view towards the end of the cycle wherein theprinting cylinder is disposed above the No. 2 etching solutions, withthe wash boom in place for cleaning off the cylinder to inhibit furtheretching action; and

FIGS. 11a, 11b, 11c and 11d is a schematic diagram of the overallcontrol circuit for the present automatic etching machine.

Reference will first be made to FIGS. 1 to inclusive of the drawingswhich show an etching machine, generally designated by the referencenumeral 10, demonstrating features of the present invention whichcomprises a machine frame 12 including spaced opposite end walls 14, 16carried on a bottom or base wall 18 and interconnected by cross rods 20,22 having a cross brace 24 welded or otherwise secured thereto.

A cylinder carrier assembly, generally designated by the referencenumeral 26, is adapted to support a printing cylinder 28 above a unitaryetching stand or trough 30 for exposure of the body section 28a of theprinting cylinder to first and second etchants contained in first andsecond wells of trough 30. The cylinder carrier assembly includes a pairof vertically movable standards 32, 34 mounted outwardly of therespective end walls 14, 16. The standards 32, 34 terminate at theirupper end in bearing-seating yokes 32a, 34a, which respectively engageball bearing mounts 36, 38 on the supporting shaft section 28b of theprinting cylinder 28. The ball bearing mounts 36, 38 are assembled onthe supporting shaft 28b in a preliminary operation, and when engaged inthe respective bearing-seating yokes 32a, 3411 on the vertically movablestandards 32, 34, provide a means for journaling the printing cylinder28 for turning movement on its axis, with the body section 28a thereofdisposed over the etching stand or trough 30. As seen best in FIG. 1 theseats 32b, 34b formed in the upper arcuate faces of the yokes 32a, 34aare of a width substantially equal to the width of the ball bearingmounts 36, 38 for longitudinally orienting the printing cylinder 28relative to the etching stand or trough 30, it being understood thatball bearing mounts 36, 38 are initially assembled in the requiredposition to establish such orientation. The standards 32, 34 are mountedfor vertical sliding movement on the outer faces of the end walls 14, 16by identical structures and accordingly it will suflice to describe thevertical guideway for the standard 34. As seen in FIG. 2, the end wall16 of the frame carries upstanding guide flanges 40, 42 which are spacedapart and cooperate to define a vertical guideway which receives theintermediate mounting section 34c of the standard 34. At its lower endthe standard 34 is formed with a cross head 34d seving as the followernut of a lead screw type raising and lowering mechanism, the standard 32being formed with a similar cross head 32d serving as a follower nut.

The lead screw raising and lowering mechanism, which is seen best inFIGS. 1 and 2, maybe operated to lower and raise the printing cylinder28 relative to the etching stand or trough 30 and includes a reversiblemotor MT3 which is mounted on the bottom wall or base 18 of the frame12. The motor MT3 is a three phase squirrel cage type of motor with twosets of contacts arranged such that reversing of any two of the threepower input leads will change the direction of the rotation of themotor, and as will appear from the description of the control circuit,includes an electric clutch CL3 and brake MB3 which facilitates theinstantaneous starting and stopping of the raising and loweringmechanisms. Extending lengthwise of the machine and above the motor MT3is a drive shaft 44 which is appropriately journaled on the end walls14, 16 of the frame. Connected between the output shaft of the motor MT3and the drive shaft 44 is a belt and pulley coupling which includes anoutput pulley 46 on the output shaft of the motor MT3, a drive pulley 48on the drive shaft 44 and a belt 50 trained over the aligned pulley 46,48. The pulley 48 may incorporate a slip clutch of well knownconstruction to facilitate the effective decoupling of the motor MT3from the drive shaft 44, if required. At its opposite ends the shaft 44terminates in respective bevel gear housing 52, 54 fixed to the outerfaces of the end walls 14, 16. The bevel gearing within the housings,which is illustrated by the dot-dash lines in FIG. 2 in the housing 54,includes one bevel gear fixed to the shaft 44 and a right angle bevelgear fixed to adjacent upstanding one of the lead screws 56, 58 whichengage respectively the follower nuts or cross heads 32d, 34d on thestandards 32, 34. Accord- 28 onto the cylinder carrier assembly 26,there is provided at the upper forward corner of each end Wall 14, 16 apivoted run-up rail (such as the rail 60 on the end wall 16) having apivotal mount 62 such that the rail may be swung from the dependingposition shown in FIG. 2

by the full lines to the horizontal position shown in FIG.

2 by the broken lines. It is contemplated that the printing cylinder 28will be moved to a loading position in front of the machine on acylinder truck 198, as shown diagrammatically in FIG. 6. The cylindertruck carries a pin 198i) engageable within the notch 60a formed in therun-up rail 60 such that the rail may be releasably secured in thehorizontal position, bridging the gap between the machine frame and thecylinder truck. This enables the cylinder 28 to be rolled on itssupporting shaft section 28b to a loading position wherein therespective ball bearing mounts 36, 38 are disposed above thebearing-seating yokes 32a, 34a of the standards 32, 34.

To enable the loading of the printing cylinder 28 onto the carrierassembly 26 and the vertical displacement thereof, the opposite endWalls 14, 16 are provided with elongated cutouts 14a, 16a providingclearance for the respective opposite ends of the supporting shaftsection 28b of the printing cylinder. The respective elongated cutoutsare bridged by loading rails 64, 66 which are pivotally and slidablymounted at the inner side faces of the respective end walls 14, 16.Since the mounting and operation of the loading rails is identical, itwill suffice to describe the mounting and operation of the loading rail64 on the inner side of the end wall 14. As seen best in FIG. 3, theloading rail 64 is formed at one end with an elongated slot 64a engagedon a pivot pin 68 fixed to the side wall 14, with the other end of theloading rail being provided with a notch 64b engageable on a pin 21fixed to the end wall 14 to releasably secure the loading rail in aposition straddling the elongated cut-out 14 and forming a substantialcontinuation of the upper edge 14b of the end wall along which theprinting cylinder 28 is rolled during its unloading from the cylindertruck. The elongated slot 64a enables the loading rail to be retractedrelative to the pin 70, such that the notch 64d may be engaged thereoverand released therefrom. Obviously during the loading of the printingcylinder 23 onto the standards 32, 34- of the carrier assembly 26, suchstandards are in their lowered position, as shown diagrammatically inFIG. 6. With the printing cylinder properly in position, the standards32, 34 are raised such that the yokes 32a, 34a engage the respectiveball bearing mounts 36, 38 to lift the printing cylinder 28 to theraised supported position, illustrated in FIGS. 1 to 3 inclusivewhereupon the loading rails 64', 66 may be moved to their respectiveretracted positions (see PEG. 3) wherein the cutouts 14a, 16a. areunobstructed and permit the raising and lowering of the printingcylinder during the etching cycle.

As a protective measure, interlock switches are incorporated into thecontrol circuit and associated with the loading rails, the cylindercarrier assembly and the raising and lowering mechanisms. Specifically,a rail position microswitch MSS is positioned to be closed when theloading rail 64 is in its retracted or clearance position (see FIG. 3)and a similar rail-position microswitch M84 is associated with theloading rail 66. The respective switches M83 and M84 are opened when theloading rails 64, 64S are in their horizontal or operative position andlock out automatic machine operation until such time as the rails areretracted to their respective clearance positions. These microswitchesprevent circuit operation in the event that the operator inadvertentlyleaves either one of the loading rails in their operative horizontalpositions and attempts to place the machine into its automatic cycle.

As a further precautionary measure, cylinder-position microswitches M85and M86 are arranged respectively to be closed by the ball bearingmounts 38, 35 when the printing cylinder is properly supported on thestandards 34, 32, the location of the microswitch MSS being shown inFIG. 2. In the event of improper alignment of the printing cylinder and/or improper seating of the bearings 36, 38 on the standards 32, 34,these microswitches will preclude circuit operation until such improperpositioning or seating of the printing cylinder 28 is corrected.

Still further, and as seen best in FIG. 2, there is provided a carrierraised-position microswitch M59 which is closed when the carrierassembly 26 and the supported printing cylinder are in the raisedposition and a carrier lowered-position microswitch M510 which is closedwhen the carrier assembly and the supported printing cylinder are in thelowered position for immersing the printing cylinder into the etchingstand or trough 3h. The carrier raised-position microswitch M89 isclosed by a switch actuating finger 72 carried by the cross head orfollower nut section 34d of the standard 34 and positioned to engage themicroswitch M59. The yoke section 34a of the standard 34- carries afurther switch actuating finger 74 which is positioned to engage andclose the microswitch MSW when the standard 34 is lowered. Theinterconnection of these interlocks as well as the previously describedinterlocks will be set forth in connection with the detailed descriptionof the control circuit.

Operatively connected to the printing cylinder 28 is a turning mechanismwhich rotates the cylinder on its axis, first in one direction during afirst phase of the etching cycle and then in the opposite direction in asecond or final stage of the etching cycle. The turning mechanism, seenbest in FIGS. 1 and 2, comprises a cylinder turning motor MT4 which ismounted on the base or bottom t5 wall 118 of the machine frame 12. Themotor MT4 is a three-phase squirrel cage motor with two sets of contactssuch that the reversing of any two of the three wires of the three phaseinput will change the direction of rotation of the motor. The outputshaft or" the motor MT4 is connected via a gear reduction unit 75through a pair of intermediate belt and pulley couplings to a turninghead 77 which is releasably secured to the cylinder supporting shaft 28boutwardly of the ball bearing mount 38. As seen best in FIG. 2, a beltand pulley housing 76 is rockably mounted on a bearing bracket 78 fixedto the machine frame and rocks by its own weight in thecounter-clockwise direction about the axis of the output shaft 80 of thegear reduction unit 75 to tension the belt and pulley couplings in thevarious vertical positions of the printing cylinder and the turning head77 Sup ported thereon. Specifically, the output shaft 80 of the gearreduction unit 75 carries a pulley (not shown) within the housing 76which pulley is coupled to a second pulley (not shown) within thehousing 76, with the latter pulley being carried on an intermediatepulley shaft 82. The pulley shaft 82 further carries an intermediatepulley 84 which is aligned with a driven pulley 86 secured to or formedintegrally with the turning head 77, with a belt 88 being trained overthe aligned pulleys 84, 86. Accordingly, in response to drive of themotor MT4 in one direction or the other, the reduced speed out-put atthe shaft 8% will be coupled via the belt and pulley coupling within thehousing 76 and the further belt and pulley couplings 84, as, 38 to thesupporting shaft 28b for the printing cylinder 28 such that the printingcylinder will be driven in the appropriate direction. It will beappreciated that this drive can be continued throughout the entireetching cycle even when the printing cylinder is being raised or loweredsince the rocking action of the pulley housing 76 about the rocking axisprovided by the output shaft 8h of the gear reduction unit 72 enablesthe automatic tightening of the belt and pulley couplings in the variouspositions of the carrier assembly.

As seen best in FIGS. 4 and 5, the laterally shiftable etchant stand ortrough 30 is seen to include a generally rectangular plastic :bodyformed with two side by side wells 96, 92. Each of the wells includes aconcave base wall 94, 96 of a curvature approximating the curvature ofthe printing cylinder with the opposite end walls of the wells beingcutout as indicated at 98 to provide for clearance for the supportingshaft section 2315 of the printing cylinder. The well 90 is adapted toreceive a prescribed quantity of a first or No. l etching solution oracid, while the well 92 is adapted to receive a prescribed quantity of asecond or No. 2 etching solution or acid.

Normally the etching stand or trough lift is disposed within the laterallimits of the machine frame 12 (see FIG. 6) but is shiftable to alaterally offset position (see FIG. 5 wherein the Well 9t} for the firstetchant is positioned for immersion of the printing cylinder 28, withthe well 92 spaced forwardly of the machine frame. The trough is mountedfor such sidewise shifting movement by a number of depending brackets 1%each of which rotatably journals a roller 1&2. Several rollers areprovided at each end of the etching stand or trough 3i), with therollers being iguidingly engaged in horizontally-extending guide flangesor rails M4, 1% fixed to the inner faces of the upstanding end walls,14, 16.

A lateral shifting mechanism is operatively connected to the etchingstand or trough 30' to periodically shift the same to a first etchingposition wherein the first etching well 90 is beneath the printingcylinder and then to a second etching position wherein the secondetching well 92 is beneath the printing cylinder. Normally the secondetching well 92 is beneath the cylinder, and as a first step in theautomatic operation, the etching stand or trough 30 is shifted laterallyfrom the starting position (see FIG. 6) to the first etching position(see FIG. 5).

The lateral shift mechanism includes a double-acting air piston andcylinder 108 which is mounted transversely of the machine frame 12 onthe cross brace 24 beneath the etching stand or trough 20. The cylinderbody 110 has appropriate air inlets at its opposite ends, with solenoidcontrolled valves SV4 and SVS selectively controlling the admission ofair to the cylinder body, as is generally understood. The piston rod112, which is driven to the left in FIG. upon admission of air via thesolenoid controlled valve SV4 and is driven to the right in FIG. 5 uponadmission of air via the solenoid controlled valve SVS, is coupled by aconnecting head 114 to a depending arm 116 fixed to the trough 30.Accordingly, upon the selected admission of air to the double-actingpiston and cylinder 108, the lateral shift of the etching standardtrough 30 may be achieved. To this end the solenoid control valves SV4,SV5 are connected in the control circuit and as will be describedachieve the lateral shifting as required during the automatic etchingcycle.

As seen in FIG. 5, further interlocking microswitches are provided toindicate the respective etching positions of the etching stand or trough30. Specifically a switchactuating finger 118 is connected to the troughat one of the rear roller-supporting brackets 108 and first and secondetching-position microswitches M87, M58 are fixed to the end wall 14 ofthe machine frame in position to be contacted and closed respectively bythe switch-actuating finger 118 in the first and second etchingpositions.

A seen best in FIG. 1, respective etchant supply systems are providedfor the first and second etching wells 90 and 92 of the etching troughor stand 30. Specifically, the first etchant supply includes a firstpositive displacement etchant pump EP1 which is connected to a pumpmotor MT1 via an electric clutch GL1. The etchant pump EP1 is connectedvia an etchant supply pipe 120 to storage or supply tanks (not shown)which is preferably located in the same room as the etching machine. Thepump EP1 delivers the No.1 etchant under pressure via the outlet pipe122 to an inlet head or nozzle 124 (see FIG. 5) which is located in theconcave base wall 94 of the well adjacent to the upper end thereof. Inthe outlet pipe 122 there is provided a normally closed inlet valve 126which is controlled by an air-operated double-acting piston and cylinder128. With the piston rod 128a in the position illustrated in FIG. 1, theinlet valve 126 is closed and when the piston rod 128a is driven downdownwardly due to the admission of air to the upper end of cylinder body128b the valve is opened. The double-acting piston and cylinder 128 isselectively actuated by a solenoidcontrolled three-way valve SV1 whichis connected in the control circuit, as will hereinafter be described.An inlet valve position micro-switch M81 is arranged to be closed whenthe piston rod 128a is in the position corresponding to the valve 126being closed. The micro-switch M81 opens in response to the opening ofthe inlet valve 126 and thereby provides an indication of the conditionof the etchant inlet valve 126.

A substantially identical second etchant supply system is provided forintroducing a prescribed quantity of the No. 2 etchant into the well 92of the etching stand or trough 30. This system includes a secondpositive displacement etchant pump EP2 coupled via an electric clutchCL2 to a pump motor MT2, with the pump having an etchant supply pipe 130connected to storage or supply tanks for the second etchant whichdeliver the second etchant via the inlet pipe 132 to an inlet nozzle orhead 134 positioned adjacent the upper edge of the concave base wall 96of the second well 92. A normally closed etchant inlet valve 136 isconnected in the inlet pipe 132 and is controlled by a double-actingpiston and cylinder 138 which is selectively actuated by a three waysolenoid controlled valve SV2. An inlet valve-position microswitch M82is provided for the second inlet valve 136, with the switch MS2 beingclosed when the valve 136 is closed.

Drain means are connected respectively to the wells 90, 92 of theetching trough 30 which are arranged to enable the drain of therespective etching solutions to a drain line. Further, provision is madefor connecting the respective wells to a catch or recovery tank 140mounted at the rear of the machine frame (as seen in FIG. 5).Specifically, the drain 142 for the first or No. 2 etchant well includesa drain pipe having a solenoid controlled valve SV6 connected in one legor branch thereof for connecting the drain via a drain hose 144 to thecatch or recovery tank and a solenoid controlled valve SV8 in a secondleg or branch thereof for connecting the drain via a further drain hose146 to a drain line in the event that the solution or acid is not to berecovered. In a similar fashion, the drain 148 for the second or No. 2etchant well 92 has one branch which is connected via a normally closedvalve 154 to a drain hose 150 connected to the recovery or catch tank140 and a second branch or leg which is connected via a solenoidcontrolled valve 5V9 to a drain hose 150 connected to the main drainline. As seen in FIG. 5, a solenoid controlled valve SV7 is effected viaa double acting piston and cylinder 152 to open the normally closeddrain valve 154 connected in the branch from the drain 148 to the drainpipe 150, with the microswitch MS11 being closed when the valve 154 isclosed. This system for the controlled connection of the drain of theNo. 2 etchant well to the recovery tank 140 will be recognized as beingidentical to the inlet valves 126, 136 and their respective controls andposition-indicating microswitches M81, M82. As will be explained inconnection with the control circuit, it is important to provide aninterlock for connection of the drain 148 to the catch tank 140 topreclude the inadvertent introduction of water into the catch tank, asmight occur if the valve 154 were opened during the washing phase of theetching cycle.

Provision is made in each of the etching wells or tanks 90, 92 for theadmission of air under pressure therein to bubble or agitate therespective etchants during the etching cycle. Identical arrangements areprovided for the admission of air to the respective wells andaccordingly it will sutfice to describe in detail only the arrangementfor the well 90, as shown best in FIG. 4. The well 90 along its lengthis formed with a number of side by side slit-like air passages 156 whichcommunicate with each other along their upper ends via a common duct orpassageway 158 formed longitudinally of the concave base wall 94 of thewell 90. At their lower ends, each of the air passages 156 is providedwith an outlet opening 160 such that air introduced into the upper endsof the passages may bubble into the etchant through the openings 160. Amanifold 162 is provided in communication with the common duct orpassageway 158, with an air inlet hose 164 being connected to themanifold for the introduction of air under pressure thereto. By theappropriate disposition of the slit-like passages 156 along the lengthof the well and the sizing of their respective outlet openings, it ispossible to maintain the etchant in a bubbly condition which promotesthe continuous replenishment of the etchant at the successive exposedsurfaces of the printing cylinder 28 and also tends to remove theetching residue. The well base wall 94 is appropriately covered with alining 166 of fibre glass or similar material which is laminated theretoto present a continuous well surface which is substantially imperviousto attack by the etchant, with the laminated lining closing off andcompleting the respective passages 156. It will be appreciated thatother arrangements are suitable for the introduction of air underpressure into the respective wells 90, 92.

Referring again to FIG. 1, there is shown a cylinder wash assembly,generally designated by the reference number 170, which includes a boomcarrier bracket 172 secured to and projecting outwardly from the endwall 14 of the machine frame 12. Mounted at the upper end of the boomcarrier bracket 172 is a boom arm 174 1 9 which has a pivotal mount 176contiguous to its outer end, the boom arm extending lengthwise of themachine in its operative or horizontal position. Extending below theboom arm 174 is the water boom 178 which is of a length to besubstantially coextensive with the printing cylinder 28 and is formed onits underside with a number of spray openings. Provision is made forintroducing water into one end of the water boom 178 via a flexiblesupply pipe 180 which includes a first branch 182 adapted to beconnected to a source of water and a second branch 184 adapted to beconnected to a back drain. A solenoid controlled two-way water inletvalve SV11 is provided in the branch 182 to control the admission ofwater from the branch or line 182 to the supply pipe 180, while asolenoid controlled water drain valve V3 is connected in the branch 184to enable back draining of the water boom 178. The water boom 178 ismovable from a substantially upright inoperative position (not shown)outwardly of the end wall 14 of the machine frame through a clockwiseswing to a substantially horizontal operative position (FIG. 1) whereinthe boom 178 is coextensive with and overlies the printing cylinder 23.The boom is moved from its substantially vertical inoperative positionto its horizontal operative position by a boom actuating mechanism whichincludes a doubleacting piston and cylinder 186 having a cylinder body186a and a piston rod 18Gb. The cylinder body 186a has a pivotal mount188 on the boom bracket 172, while the piston rod 186b has a pivotalcoupling 190 to the extension of the boom arm outwardly of the pivotalmount 176. Air is selectively introduced into the double-acting pistonand cylinder 186 via an air inlet hose 192 which is selectivelyconnected through a four-way solenoid controlled valve SV10- with onebranch 194 to the upper end of the cylinder body 186a and with anotherbranch 196 to the lower end thereof. Accordingly, upon admission of airunder pressure via the air inlet hose 192 and the branch hose 196 to thelower end of the double-acting piston and cylinder, the boom assembly isswung to the operative position shown in FIG. 1; and upon admission ofair under pressure to the upper end of the cylinder body 186a via thebranch hose 194, the boom assembly is moved to the retracted orinoperative position.

Preliminary to reference to the schematic control diagram of FIGS. 11ato 11d inclusive, reference will be made to FIGS. 6 to 10 inclusive fora brief description of the sequence of operations performed by theetching machine illustrated in FIGS. 1 to 5.

At the start of operations, the printing cylinder 28 is brought to aposition in front of the machine frame 12 by the cylinder truck or cart198. The upper supporting edges 198a of the truck or cart supports therespective oppositely directed shaft sections 281) of the printingcylinder 28, such that the printing cylinder may be rolled from the cantonto the upper supporting edges 14b, 16b of the end walls of the machineframe, with the run-up rails 69 and the loading rails 64, 66facilitating the positioning of the printing cylinder 28, as shown bythe dotted line in FIG. 6, to be engaged and lifted by the respectivevertically movable standards 32, 34. It will of course be appreciatedthat this manner of loading is merely illustrative and in some instancesoverhead cranes will be used to transport the printing cylinders to aposition for engagement and support in the etching machine. The operatorthen places the carrier assemby 26 into operation to lift the printingcylinder 28 to the elevated clearance position, as shown in FIG. 7,wherein the loading rails 64, 66 may be dropped to clear the machine foroperation, the cart or 198 being likewise moved away. When the machineis placed into operation, as may be appreciated by progressivelyinspecting FIGS. 6 and 7, the trough 3t} shifts laterally in a forwarddirection to bring the well 90 for the No. 1 etchant beneath thesupported printing cylinder. Thereupon the printing cylinder is loweredinto the well 90, as may be appreciated by progressively inspectingFIGS. 7 and 8. After a prescribed time interval in the No. 1 etchant,the carrier assembly lifts the printing cylinder to the clearanceposition (e.g. the FIG. 7 position) whereupon the trough 30 shiftslaterally rearwardly to bring the No. 2 etchant well beneath theprinting cylinder. When the trough is repositioned, the carrier assembly26 lowers the printing cylinder into the second etchant, as is see-n inFIG. 9, it being understood that the printing cylinder moves to the FIG.7 position intermediate the positions illustrated respectively in FIGS.8 and 9. After a prescribed time in the second etchant, the carrierassembly lifts the printing cylinder to its elevated position whereuponthe wash boom 178 is brought to its horizontal position coextensive andover the printing cylinder for a wash interval, as showndiagrammatically in FIG. 10.

Referring now specifically to FIGS. 11a, 11b and 11c there is shown theoverall schematic diagram for my improved automatic printing cylinderetching machine, the motor energization circuitry being shown in FIG.11d. The control circuit is energized from an appropriate source ofalternating current over a double pole single-throw main control switch200 to the AC. control lines 202, 204. Connected across the lines 202,204- is a No. 1 etchant supply control generally designated by thereference numeral 206, which may be placed into operation prior to theautomatic machine cycle to introduce :a prescribed quantity of the No. letchant into the well or tank 90. The control 206 includes a normallyclosed stop push button 268 connected in series with a normally openstart push button 210 and the energization coil of a relay A. The relayA includes a holding circuit shunting the start-push button 210, whichholding circuit includes the relay contact A1 in series with thenormally closed contact AA1 of the first etchant supply timer AA.Simultaneous with the energization of the relay A, the solenoidcontrolled valve SV1 is activated which via the double-acting piston andcylinder 128 opens the normally closed etchant supply inlet valve 126for introduction of the etching solution into the No. 1 tank. Inresponse to opening of the valve 126, the valve-position microswitch M51is closed to complete the energization circuit for the slow releaserelay B, this circuit having been previously conditioned by energizationof the relay A and the closing of the contact A2 in series with themicroswitch MSl. When the relay B is energized, the contact B1 closes toconnect the relay C across the line which via its contact C1 (see FIG.11d) energizes the pump motor MT1 for the first etchant sup-F plysystem. As seen in FIG. the coil for the clutch (3L1, which couples themotor MT1 to the fixed displacement pump EP1, is energized from a fullwave rectifier 216 which has its output leads 212, 214 connected acrossthe clutch GL1 which is in series with a normally open relay contact A3,the latter being closed to condition the circuit in response to closingof the relay'A. The full wave rectifier 216 is connected across thelines via the leads 218, 226. Since the fixed displacement pump willpump a prescribed quantity of the first etchant in accordance with thesetting of the timer AA an accurate means is provided for controllingthe admission of the No. 1 etchant to the well 90. After the timer AAtimes out, the normally closed contact AA1 in the holding circuit forthe relay A opens and via contact A2 deenergizes the relay B after thetime delay of relay B. When relay B is deenergized, contact B1 reopensand recycles the timer AA and deenergizes the pump motor MT1 for the No.l etchant pump EPl via the contact B1. The provision for slow release inthe relay B assures that relay A will drop out by opening of the contactAA1 before the timer AA is reset for the next cycle whereupon thecontact AA1 is closed.

A No. 2 etchant supply control, generally designated by the referencenumeral 222, is provided for introducing a prescribed quantity of theNo. 2 etchant into the well or tank 92. This control isidentical to.thecontrol 206 and includes a normally closed stop push-button 224, anormally open start push-button 226 in the energization circuit for therelay C. The relay C includes a holding circuit shunting the start-pushbutton 226 which holding circuit includes the relay contact D1 in serieswith the normally closed contact DB1 of the second etchant supply timerBB. Simultaneous with energization of the relay B in response to thedepression of the start push-button the solenoid controlled valve SV2 isactivated which via the double acting piston and cylinder 138 opens thenormally closed etchant supply inlet valve 136 for introducing theetching solution into the No. 2 tank. In response to opening of thevalve 136, the valve position microswitch M52 is closed to complete theenergization circuit for the slow release relay E, this circuit havingbeen previously conditioned by energization of the relay D and closingof the contact D2 in series with the microswitch M52. When the relay Eis energized, the contact E1 closes to connect the relay Y across theline which via its contacts Y1 (see FIG. 11d) energizes the pump motorMT2 for the second etchant supply system. As seen in FIG. 110, the coilfor the clutch CL2, which couples the pump motor MT2 to the fixeddisplacement pump EP2 is energized previously in response to closing ofthe contact D3 of the relay D. In response to the closing of the contactD1 the timer BB which establishes the interval during which the fixeddisplacement pump EP2 is effective to supply the No. 2 etchant to thetank 92 begins its timing function. When the timer BB times out thecircuit is reset as previously described in connection with the control206.

Reference will now be made to the automatic cycle control which is seento include a stop push-button 228 and a start push-button 230 in serieswith a relay F and the interlock microswitches M83, M84, M55, and MSG,as well as the normally open contact J1 of the relay J. Themicroswitches MS3 to M86 inclusive are closed when the loading rails arein their respective retracted positions and the cylinder is properlycradled in the carrier assembly. The contact J1 closes to complete theenergization circuit for the relay F when relay I (see FIG. 11b) isenergized. Relay J is connected across the lines via a stop push-button232 (its remote counterpart 232a) and the microswitch M89 whentransferred. Microswitch M89 transfers when the carrier assembly is inthe raised position to complete the energization circuit for the relay 1and in the event that the relay J is not so energized the operatordepresses the raise-carrier pushbutton 234 in series with themicroswitch M59 in its untransferred position to elevate the carrierassembly and the printing cylinder preliminary to the automatic cycle.With the relay J energized, the contact J1 completes the energizationcircuit for the relay F which immediately places into operation theautomatic turn mechanism for the printing cylinder. The automatic turnmechanism includes a relay G which connects the turn motor MT3 acrossthe lines via the contact G1 to turn the motor in one direction and arelay H having contacts H1 for connecting the motor MT3 across the lineto turn in the opposite direction. The motor is connected to aconventional variable speed drive 236 having a speed controlpotentiometer 238, with the variable speed drive being connected acrossthe lines via the power transformer 240. The clutch CL3 for the motorMT3 is energized in response to closing of either of the contacts G3,H3. The relays G and H are energized in alternation over thetransferable contact 11 over the closed conditioning contact P2 of therelay F, with the relays G and H having respective lockout contacts G2,H2 in their associated circuits.

Contact I1 is transferred under the control of two conventional timersCC and DD each of which timers includes an internal clock motor whichafter a prescribed time interval achieves an external control function.When the lockout contct F2 closes the timer CC star-ts its timinginterval, receiving its power via the normally closed contact DD1 of thetimer DD. When the timer CC times out it closes its normally openedcontact CC1 to complete an energization circuit for a slow release relayI which immediately transfers its contact 11 to deenergize the relay Gand stop the motor MT3 through its contact G1, with the variable speedclutch coupling being deenergized via the contact G3. Relay H is thenenergized over the transferred contact 11, starting the motor MT3 in thereverse direction through contact H1, with the reenergization of thevariable speed clutch through the contact H3. Further, relay I viacontact 12 starts the timer DD which after it times out opens the relayDD1 to reset the timer CC, resetting of the timer CC opens the contactCC1 which in turn disrupts the energization circuit for the slow releaserelay I, with the relay I allowing for the timer CC to be reset beforerelay I drops out. When relay I finally drops out, contact 12 opens,resetting the timer DD which in turn closes the contact DD1 and againrepeats the timing cycle via the timer CC. As will be describedhereinafter, the normally opened contact end N1 serves as a lockout forprecluding reversal of the turn direction of the printing cylinder atsuch times during the operating cycle when the printing cylinder is inthe raised position above the etching stand or trough 30, since duringthe periods of transfer it is important that the cylinder continue torotate in the same direction to maintain on the surface thereof asubstantially fixed quantity of the No. 1 etching solution.

Returning now to the automatic cycle, simultaneous with the energizationof the relay 1 (FIG. llb), the relay K is energized over the transferredmicroswitch M59 which remains in the requisite position to complete theenergization circuits for the relays J, K when the carrier assembly isin the elevated position. Upon energization of relay K, the contact K1closes in order to condition the circuit for energization of the relay Swhich is effective to shift the etching stand or trough 30 into the No.1 etching position for exposure of the printing cylinder to the No. 1etchant in the well 90. As will subsequently be described, relay K andcontact K1 are opened at a prescribed time in the cycle uponenergization of the relay 0 and opennig of the contact 01 to serve as alockout.

Energization of the relay F opens a number of relay contacts associatedrespectively with the push button controls to preclude manual operationof the machine and also closes a number of other contacts for thepurpose of conditioning certain circuits for operations. Specifically,contact F6 (FIG. l lb) is closed which completes an energization circuitvia closed contact K-1 of the relay K for the relay 5. The relay Sincludes a contact S1 FIG. 110) which connects the solenoid-controlledvalve SV4- across the lines 202, 204. As seen in FIG. 5, energization ofthe valve SV4 introduces air under pressure to the right end of thedouble-acting piston and cylinder 108 which is effective to shift theetchant trough 30 laterally to the No. l etching position illustrated inFIG. 5 wherein the well for the No. 1 etchant is positioned to receivethe printing cylinder 28. When the etching stand or trough 30 arrives atthe laterally-shifted position shown in FIGS. 5 and 7, the firstetching-position microswitch M87 is closed to indicate the positioningof the etching stand for the first immersion of the printing cylinder28. As seen in FIG. 11b, the first etchingposition microswitch M87 isconnected in a series energization circuit for the relay M whichenergization circuit includes the normally closed stop push button 232,and its remote counterpart 232a, the untransferred carrier-loweredposition microswitch M810, the closed conditioning contact P4 of therelay F, the now closed microswitch M87, the lockout contact 02 and thelockout contact L2. Upon energization of the relay M, the

motor MT4 (see FIG. 11d) of the carrier raising and lowering mechanismis connected across the three phase line via the stator contacts M1 forrotation of the motor in a direction appropriate to lower the carrierassembly 26 for immersing the printing cylinder into the No. 1 etchantin the first well or tank 96. It will be appreciated that provision ismade for the manual lowering of the carrier assembly by a secondaryenergization circuit for the relay M via the untransferredcarrier-lowered position microswitch M510, the normally opencarrierlowering push button 244 (and its remote counterpart 244a) andthe normally closed lockout contact L2. Relay M locks across the linevia conditioning contact F and holding contact M3 shunting the pushbutton 244. The lock-out contact L2 precludes energization of the relayM when the relay L for the carrier-raising mechanism is energized andconversely the lockout contact M2 precludes energization of the relay L.When the carrierlowering push button 244 is depressed and the relay M isenergized, the contact M3 which is connected in series with the normallyclosed contact F5 is closed which completes the holding circuit for therelay M, which holding circuit is disrupted when the microswitch M810transfers to indicate that the carrier assembly has reached thelowermost limit of its travel as established by the positioning of themicroswitch M818. It will of course be appreciated that the provisionfor manual lowering of the carrier assembly via depression of thenormally open push button 244 is effectively locked out by the openingof the normally closed contact P5 of the relay F which is energizedduring the automatic etching cycle. Further and in order to accuratelyestablish the raised and lowered positions of the cylinder carrierassembly 26, the motor MT4 of the raising and lowering mechanism isprovided with a direct current electric brake M134 (FIG. llc) which isconnected in the output leads 212, 214 of the full wave rectifier bridge216. The brake M134 is connected in a series circuit including thecontacts M3, L3 and a brake-setting potentiometer 217. Contacts M3, L3are normally closed and accordingly a braking force, determined by thesetting of the potentiometer 217, is applied to the motor MT4. When themotor is placed in operation for either the raising or lowering motion,depending upon the energization of the relays L and M respectively, theassociated contact L3, M3 is opened to remove the braking force.

Returning now to the automatic sequencing, the closing of the firstetching position microswitch M87 causes the relay M to energize whichconnects the motor MTE- to the line via the contacts M1 in a directionappropriate to lower the carrier assembly 26 and the printing cylinder23 into the No. 1 etchant. When the carrier assembly reaches its loweredposition, the carrier-lowered microswitch MSltl transfers to complete anenergization circuit for the relay N and simultaneously deenergizes therelay M which stops the carrier raising and lowering motor MT4, andapplies the brake M34. Energization of the relay N closes the contactN2, which via the closed conditioning contact F6, connects the firstetching timer EE across the lines for initiating the timing of theimmersion of the printing cylinder 28 in the first or No. 1 etchingsolution. Closing of the contact N2 also completes an energizationcircuit for the relay 0 which as previously indicated includes anormally closed lockout contact 01 in the energization circuit for therelay K. At this time the lookout contact 01 is opened to precludeenergization of the relay K until such time as the entire machine cycleis completed. Further the relay 0 includes the normally closed contact02 in the energization circuit for the relay M which also precludesenergization of the relay M over the circuit including the firstetching-position microswitch M87. Still further, the relay 0 includes anormally open contact 03 shunting the contact N2 of the relay N whichprovides a holding circuit for the timer EE since such timers are i4connected in cascade and the circuit is arranged such that the timersshould not drop out or be reset incident to the raising and lowering ofthe printing cylinder between immersions in the first and second etchingsolutions.

After timing out of the first immersion timer EE, which may be of theorder of 12 to 15 minutes, its contact EEl closes to complete anenergization circuit for the relay P over the lookout contact Q2. RelayP includes a normally-open contact P 1 which via the lockout contact M2connects the relay L across the line. Energizetion of the relay Lconnects the motor MT4- across the three phase line via the statorcontacts L1 which is effective to cause the carrier assembly 26 to movefrom the lowered position toward the raised position. When the carrierassembly 26 arrives at the raised position, the carrier raised-positionmicroswitch M89 transferred to energize the relay I which will initiatethe next phase of the automatic operation which is recalled to be thetransfor of the etching stand or trough to the second or No. 2 etchingposition wherein the well 92 containing the No. 2 etching solution isbeneath the printing cylinder. During this phase of the operation, relayK is not energized since the lockout contact 01 of relay 0 is opened andprecludes energization of the relay K over the circuit provided by thetransferred microswitch M89. However, energization of the relay J hasclosed the normally opened contact I2 which open closing of contact EElenergizes the relay Q and the first drain interval timer FF.Energization of the relay Q closes the contact Q3 to lock the relay Qacross the line, opens the lockout contact Q2, in the circuit of relay Pand closes the contact Q1 to condition the energization circuit forrelay M containing the closed conditioning contact F4, the opened secondetching-position microswitch M88, and the lockout contacts Q2, L2.Accordingly, upon transfer of the etching stand or trough to the No. 2etching position, as shown diagrammatically in FIG. 9 and as indicatedby the closing of the second etching-position microswitch M58, as willsubsequently be described circuits will be conditioned for lowering ofthe carrier assembly to immerse the printing cylinder into the second orNo. 2 etchant in the well 92. After the drain interval timer FF timesout, the contact FFl closes to connect the relay R across the line.Energization of the relay R closes its contact R1 (see FIG. 110) whichcompletes the energization circuit for the solenoid controlled valve SVSWhich admits air under pressure tothe left end of the cylinder body 11sof the double-acting piston and cylinder 1% (see FIG. 5) which drivesthe etching stand or trough laterally to the right in FIG. 5 to bringthe well 92 containing the No. 2 etchant beneath the printing cylinder.When the etching trough 39 reaches the second etching position themicroswitch M88 wil be closed when contacted by the actuating finger 118which completes the energization circuit for the relay M as aforesaidand activates the motor MT4 via its stator contacts M1 to lower thecylinder carrier assembly to immerse the printing cylinder into the No.2 etching solution. When the carrier assembly reaches its loweredposition, the actuating finger 74 :on the standard 34 will contact andtransfer the carrier lowered-position microswitch MSllt) whichinterrupts drive to the motor MT4, with the carrier assembly in thelowered position. Transfer of the carrier-lowered position microswitchM810 completes an energization circuit for the relay N which closesrelay contact N3 in the energization circuit for the second etchantimmersion interval timer GG. The timer GG is connected across the linevia the closed contact FFl of the drain interval timer FF, the contactN3,

, and the conditioning contact P8 of the energized relay F.

Further, relay T is energized which closes its contact T1 and connectsthe timer GG across the line until such time as the control circuit isreset. After the prescribed immersion time in the second etchingsolution, which may be of the order of 12 to 15 minutes, the timer GGtimes out and closes its cont-act GGl toconnect the second draininterval timer HH across the line to establish the requisite drainperiod over the second etching well or trough 92. It will of course beappreciated that in certain cases it may not be necessary to provide forone or both of the drain interval timers FF and HH and these may beeliminated by merely eliminating the timers and their respectivenormally-open contacts FFI and HI-Il. Simultaneous with the energizationof the second drain interval timer HH, the relay U is energized whichvia the contact U1 completes an energization circuit for the relay Nover the untransferred carrier raised position microswitch MS9, thecontact U11 which shunts the carrier raising push button 234 and itsholding contact L3, and the lockout contact M2. Energization of therelay L connects the motor MT4 of the carrier raising and loweringmechanism across the line via the stator contact L1 to raise thecylinder carrier assembly 26 to the elevated position above the secondetching well 92, as shown diagrammatically in FIG. 10, for the seconddrain time interval.

Further, energization of the relay U closes the contact U3 (FIG. 11c)which connects the solenoid controlled valves SV6 and SV7 across theline for their respective control function. Specifically, the solenoidcontrolled valve SV6 directly connects the drain 142 from the well 90for the No. l etching solution to the catch tank via the drain hose 144.The solenoid controlled valve SV7 operates the double-acting piston andcylinder 152 which opens the drain valve 154 for connecting the drain148 for the well 92 for the No. 2 etching solution to the catch tank 140via the drain hose 152. With respect to the drain controls, it is notedthat the contact P10 is closed during the automatic cycle such thatclosing of the contact U3 is effective to open and operate therespective drain systems for the first and second wells 90, 92.Provision is made for connecting the No. l etchant well 90 to the catchtank 44 manually by a switch 246 which is connected via a lockoutcontact F9 to the coil of the valve SV6. Similarly switch 248 isconnected in a series energization circuit for the coil of the valveSV7, with the energization circuit including the lockout contact F11.Accordingly, at any time other than during the automatic cycle when therespective lockout contacts F9, F11 are opened, the operator may closeeither of the switches 246, 248 to connect the associated well to thecatch tank 144 for draining the contents thereof.

Returning to the automatic operation, after the second drain timeinterval timer HH times out, contact HHl closes to initiate operation ofthe timer 1] which is identical in construction to the timers CC, DDemployed in the control for the turning mechanism of the printingcylinder. Simultaneous with the energization of the timer II, the relayV is likewise energized which opens the contact V1 (see FIG. 110) inseries with contact U3 in the energization circuit for the solenoidcontrolled valves SV6, SV7 which closes the drain connection from therespective wells 90, 92 to the catch tank. The closing of the drainvalve 154 for the well 92 of the No. 2 etchant is signalled by theclosing of the drain valve-position microswitch M511 which is connectedin a series circuit with the contact V2 of the relay V and the solenoidcontrolled valve SV9 for connecting well 92 to the drain pipe 150. Onlyupon energization of the relay V and signalling via the closing of themicroswitch MS11 that the drain connection to the catch tank is closed,will the circuit be completed for connecting the well 92 to the drain.This avoids the possibility of inadvertently draining the contents ofthe well 92 (which receives water during the washing phase of theautomatic cycle) into the catch tank.

Closing of the microswitch MS11 also completes an energization circuitfor the solenoid controlled valve SV10 of the double-acting piston andcylinder 186 of the boom lowering and raising control for the cylinderwash assembly 170. The energization circuit for the valve SV10 iscompleted via the closed contact V2, the closed microswitch MS11 and theclosed lockout contacts F15, F16. provision is likewise made for themanual operation of the boom lowering and raising control by a switch250 which is connected via the lockout contact F12 of the relay F to thesolenoid coil of the valve SV10. Accordingly, when not in the automaticcycle, closing of the switch 250 will enable the operator to lower theboom into the operative or horizontal position illustrated in FIG. 1.

Returning again to the automatic operation, the lowering of the boom tothe horizontal or operative position shown in FIG. 1 will close theboom-position microswitch M812. As seen in FIG. 11c, the boom-positionmicroswitch M512 completes an energization circuit for the solenoidcontrolled water inlet valve SV11, the energization circuit includingthe closed contact V2, the closed microswitch M811, the lockout contactF15, the normally closed contact X1 of the relay X, and the closedboomposition microswitch M812. Simultaneous with the energization of thewater inlet valve SV11 the relay Z is energized which via the contact V2(FIG. 11b) closes the normally energized and opened back drain valveSV3. The solenoid controlled back drain valve SV3 is normally connectedacross the line via the normally closed contact Z2, such that the drainvalve SV3 remains opened for so long as the boom is in the upright orretracted position. Only when water is admitted to the water inlet pipevia the water inlet valve SV11 (and when the boom is down as signalledby the closing of the microswitch M812), is the back drain valve SV3allowed to close.

Further energization of the relay Z via the contact Z1 (FIG. 11b)initiates the operation of the wash or spray interval timer J J which isset to establish a prescribed wash time interval for the boom over thesecond etching well 92, with the drain water from the printing cylinderbeing caught in the well and passed to the main drain via the openeddrain valve 5V9. When the wash and spray timer 1] times out, its contactJ11 closed to complete an energization circuit for the slow releaserelay W. Energization of the relay W, closes the contact W1 whichconnects a water drain interval timer KK across the line. The timer KKincludes a normally closed contact KKI in the energization circuit forthe relay F (see FIG. 11a). Simultaneous with the energization of thetimer KK and in response to the closing of the contact W1, the relay Xis energized. Energization of this relay X opens the contact X1 (seeFIG. 11c) which disrupts the energization circuit for the water inletvalve SV11 which shuts off the water supply to the boom and alsodeenergized relay Z which again opens the back drain valve SV3 byclosing contact Z2. Finally, when the timer KK times out, the contactKKI opens and the energization circuit for the relay F is disruptedwhich deenergizes the relay F and recycles the control for the nextautomatic sequence of operations.

As shown in FIG. 11b, a manual push button control is provided forselectively positioning the etching trough or stand 30 in the first orsecond etching positions. Specifically ,a normally open push button 260is connected via lockout contact F7 to the line 202 and via a furtherlockout contact provided by the push button 262 to the relay S whichrelay is effective to laterally move the etching stand 30 into the firstor No. 1 etching position. In the event that someone accidentallydepresses the push button 262 while also depressing the push button 260,the energization circuit will not be completed for the relay S. In asimilar fashion, the push button 262 when depressed provides anenergization circuit over the push button 260 and the lockout contact F7for the relay R which is effective to laterally displace the etchingstand to the second or No. 2 etching position.

As seen in FIG. 11c, provision is made for manually opening the drainvalve SV9 for the well 92 for draining the second etchant. This isachieved by a drain valve switch 266 connected in a series circuit withthe lockout 17 contact F13 for connecting the solenoid control valve SV9across the line. During the automatic cycle of operation the switch 266is locked out by opening of the contact F 13.

Still further provision is made for the manual washing of printingcylinder by a circuit (FIG. 110) including a water pray switch 268connected over the lockout contact F14, the normally closed relaycontact 1, and the boomposition microswitch M512 to the water inlet boomcontrol valve SV11. This manual control is locked out until such time asthe boom is in the horizontal or operative position by the microswitchM812 and is completely locked out of the circuit during the automaticoperation by opening of the lockout contact F14.

Still further, provision is made for opening the drain valve 8V8 of thewell 90 for the first etching solution. As seen in FIG. 110, the drainopening switch 270 is connected in series with a lockout contact F17 tothe solenoid control valve 8V8. Whenever the operator desires, theswitch 270 may be closed to drain the well 90, it of course beingunderstood that the lockout F17 precludes such drain during theautomatic cycle.

What I claim is:

l. A machine for etching printing cylinders comprising a frame, aunitary trough member mounted on said frame and having side by sidewells adapted to contain quantities of first and second etchantsrespectively, a carrier member adapted to support a printing cylinderabove said trough member, means for turning said printing cylinder onits axis, means operatively engaging and mounting one of said membersfor vertical movement relative to the other of said members such thatsaid printing cylinder may be subjected to the action of said etchants,raising and lowering mechanisms operatively connected to the verticallymovable member for effecting vertical movement thereof relative to theother member, means operatively engaging and mounting said other memberfor lateral movement relative to said vertically movable member suchthat said printing cylinder may be subjected in succession to the actionof said first and second etchants, shifting mechanisms operativelyconnected to the laterally movable member for effecting lateral movementthereof relative to the vertically movable member, and means forcoordinating said raising and lowering mechanisms and said shiftingmechanisms.

2. A machine for etching printing cylinders comprising a frame, aunitary trough member mounted on said frame and having side by sidewells adapted to contain quantities of first and second etchantsrespectively, a carrier member adapted to support a printing cylinderabove said trough member, means operatively engaging and mounting saidcarrier member for vertical movement relative to said trough member suchthat said printing cylinder may be subjected to the action of saidetchants, raising and lowering mechanisms operatively connected to saidcarrier member for elfecting vertical movement thereof relative to saidtrough member, means operatively engaging and mounting said troughmember for lateral movement relative to said carrier member such thatsaid printing cylinder may be subjected in succession to the action ofsaid first and second etchants, shifting mechanisms operativelyconnected to said trough member for effecting lateral movement thereofrelative to said carrier member. and means for coordinating said raisingand lowering mechanisms and said shifting mechanisms.

3. A machine for etching printing cylinders comprising a frame, a pairof standards, vertical guide means operatively engaging and mountingsaid standards on said frame for vertical movement, means on the upperends of said standards adapted to engage and support said printingcylinder for rotation on its axis, an etching horizontal movement withsaid first well normally disposed below said printing cylinder, meansoperatively connected to said standards for moving said standardsvertically to lower and raise said printing cylinder relative to saidwells such that said printing cylinder may be subjected to the action ofthe etchants in said first and second wells, means operatively connectedto said trough for moving said trough horizontally to shift said secondwell below said printing cylinder, and control means for coordinatingthe movements of said standards and said trough such that said printingcylinder may be lowered into said first well, raised from said firstwell, and after shifting of said trough, lowered into said second well.

4. A machine for etching printing cylinders comprising a frame, a pairof standards, vertical guide means operatively engaging and mountingsaid standards on said frame for vertical movement, means on the upperends of said standards adapted to engage and journal said printingcylinder for rotation on its axis, turning means adapted to operativelyengage said printing cylinder for rotating said printing cylinder on itsaXis, an etching trough including first and second side by side wells,lateral guide means operatively engaging and mounting said troughintermediate said standards for side to side horizontal movement withsaid first well normally disposed below said printing cylinder, meansoperatively connected to said standards for moving said standardsvertically to lower and raise said printing cylinder relative to saidwells such that said printing cylinder may be subjected to the action ofthe etchants in said first and second wells, means operatively connectedto said trough for moving said trough horizontally to shift said secondwell below said printing cylinder, and control means for coordinatingthe movements of said standards and said trough such that said printingcylinder may be lowered into said first well, raised from said firstwell, and after shifting of said trough, lowered into said second well.

5. A machine for etching printing cylinders comprising a frame, carriermeans on said frame adapted to support said printing cylinder, anetching trough including at least one well mounted on said frame withsaid well disposed below said printing cylinder, raising and loweringmeans operatively connected to said carrier means for moving saidcarrier means to lower said printing cylinder relative to said well suchthat said printing cylinder may be subjected to the action of an'etchant in said well and raised to interrupt such action, a washingboom, means operatively connected to and mounting said boom for movementfrom a clearance position to an operative position overlying andsubstantially coextensive with said printing cylinder, actuating meansoperatively connected to said boom for moving said boom from saidclearance position to said operative position, and coordinating meanscontrolled by said raising and lowering means and controlling saidactuating means for moving said boom into said operative position afterraising of said printing cylinder relative to said well.

6. A machine for etching printing cylinders comprising a frame, a pairof standards, means operatively engaging and mounting said standards onsaid frame for vertical movement, means on the upper ends of saidstandards adapted to engage and journal said printing cylinder forrotation on its axis, turning means adapted to operatively engage saidprinting cylinder for rotating said printing cylinder on its axis, anetching trough including at least one well mounted on said frameintermediate said standards with said well disposed below said printingcylinder, raising and lowering means operatively connected to saidstandards vertically to lower said printing cylinder relative to saidwell such that said printing cylinder may be subjected to the action ofan etchant in said well and raised to interrupt such action, a washingboom, means operatively connected to and mounting said boom for movementfrom a clearance position to an operative position overlying andsubstantially coextensive with said printing cylinder, actuating meansoperatively connected to said boom for moving said boom from saidclearance position to said opertaive position, and coordinating meanscontrolled by said raising and lowering means and controlling saidactuating means for moving said boom into said operative position afterraising of said printing cylinder relative to said well.

7. A machine for etching printing cylinders comprising a frame, a pairof standards, vertical guide means operatively engaging and mountingsaid standards on said frame for vertical movement, means on the upperends of said standards adapted to engage and journal said printingcylinder for rotation on its axis, an etching trough including first andsecond side by side walls, lateral guide means operatively engaging andmounting said trough intermediate said standards for side to sidehorizontal movement, a raising and lowering mechanism operativelyconnected to said standards for moving said standards vertically tolower and raise said printing cylinder relative to said etching troughsuch that said printing cylinder may be subjected to the action of theetchants in said first and second wells, a lateral shift mechanismoperatively connected to said trough for moving said trough horizontallyto shift said etching trough relative to said printing cylinder, meansincluding a first pump for feeding a prescribed volume of a firstetchant to said first well, means including a second pump for feeding aprescribed volume of a second etchant to said second well, and a controlfor coordinating the certical movement of said standards, the horizontalmovement of said etching trough and the delivery of said first andsecond etchants to said first and second wells.

8. A machine according to claim 7 including first and second agitatingmeans in operative relation to said first and second wells for agitatingsaid first and second etchants during the exposure of said printingcylinder to the action of said first and second etchants.

9. A machine for etching printing cylinders comprising a frame, a pairof standards, vertical guide means operatively engaging and mountingsaid standards on said frame for vertical movement, means on the upperends of said standards adapted to engage and journal said printingcylinder for rotation on its axis, turning means adapted to operativelyengage said printing cylinder for rotating said printing cylinder on itsaxis, an etching trough including first and second side by side wells,lateral guide means operatively engaging and mounting said troughintermediate said standards for side to side horizontal movement, araising and lowering mechanism operatively connected to said standardsfor moving said standards vertically to lower and raise said printingcylinder relative to said etching trough such that said printingcylinder may be subjected to the action of the etchants in said firstand second wells, a lateral shift mechanism operatively connected tosaid trough for moving said trough horizontally to shift said etchingtrough relative to said printing cylinder, means including a first pumpfor feeding a prescribed volume of a first etchant to said first well,means including a second pump for feeding a prescribed volume of asecond etchant to said second well, and a control for coordinating thevertical movement of said standards, the horizontal movement of saidetching trough and the delivery of said first and second etchants tosaid first and second wells.

10. A machine according to claim 9 including means operatively connectedto said turning means for reversing the direction of turning of saidprinting cylinder during exposure to said first and second etchants.

11. A machine for etching printing cylinders comprising a frame, a pairof standards, vertical guide means operatively engaging and mountingsaid standards on said frame for vertical movement, means on the upperends of said standards adapted to engage and journal said printingcylinder for rotation on its axis, turning means adapted to operativelyengage said printing cylinder for rotating said printing cylinder on itsaxis, an etching trough includ ing first and second side by side wells,lateral guide means operatively engaging and mounting said troughintermediate said standards for side to side horizontal movement, araising and lowering mechanism operatively connected to said standardsfor moving said standards vertically to lower and raise said printingcylinder relative to said etching trough such that said printingcylinder may be subjected to the action of the etchants in said firstand second wells, a lateral shift mechanism operatively connected tosaid trough for moving said trough horizontally to shift said etchingtrough relative to said printing cylinder, means including a first pumpfor feeding a prescribed volume of a first etchant to said first well,means including a second pump for feeding a prescribed volume of asecond etchant to said second well, a control for coordinating thevertical movement of said standards, the horizontal movement of saidetching trough and the delivery of said first and second etchants tosaid first and second wells, a washing boom mounted for movement into anoperative position overlying and substantially coextensive with saidprinting cylinder, and an actuating mechanism controlled by said raisingand lowering mechanism for moving said boom into said operative positionin timed relation to the raising of said printing cylinder.

12. A machine for etching printing cylinders comprising a frame, carriermeans on said frame adapted to support said printing cylinder, anetching trough including two wells mounted on said frame with said wellsdisposed below said printing cylinder, means for moving said troughtransversed to its length for selective movement between a firstposition wherein said printing cylinder is in vertical alignment with afirst well, and a second position wherein said printing cylinder is invertical alignment with a second well, raising and lowering meansoperatively connected to said carrier means for moving said carriermeans to lower said printing cylinder relative to said trough such thatsaid printing cylinder may be subjected to the action of an etchant inone of said wells and raised to interrupt said action, supply means foran etchant, pump means for the delivery of a selected amount of anetchant to one of said wells, a washing boom, means operativelyconnected to and mounting said boom for movement from a clearanceposition to an operative position overlying and substantiallyco-extensive with said printing cylinder, actuating means operativelyconnected to said boom for moving said boom from said clearance positionto said operative position, and coordinating means controlled by saidraising and lowering means and controlling said actuation means formoving said boom into said operative position after raising of saidprinting cylnder relative to said well and for coordinating the movementof said raising and lowering means with the transverse movement meansand with the pump means for selectively cycling said printing cylinderthrough an etching operation with selective amount of etching beingaccomplished in said first well and in said second well.

13. A machine for etching printing cylinders comprising a frame, carriermeans on said frame adapted to support said printing cylinder, anetching trough including two wells mounted on said frame with said wellsdisposed below said printing cylinder, means for moving said troughtransversed to its length for selective movement between a firstposition wherein said printing cylinder is in vertical alignment with afirst well, and a second position wherein said printing cylinder is invertical alignrnent with a second well, raising and lowering meansoperatively connected to said carrier means for moving said carriermeans to lower said printing cylinder relative to said trough such thatsaid printing cylinder may be subjected to the action of an etchant inone of said wells and raised to interrupt said action, supply means foran etchant, pump means for the delivery of a selected amount of anetchant to one of said wells, and coordinating means for coordinatingthe movement of said raising and lowering means with said transversemovement means and with said pump means for selectively cycling saidprinting cylinder through an etching operation with selective amounts ofetching being accomplished in said first well and in said second well.

14. A machine for etching printing cylinders comprising a frame, aunitary trough member mounted on said frame and having side by sidewells adapted to contain quantities of first and second etchantsrespectively, a carrier member adapted to support a printing cylinderabove said trough member, means operatively engaging and mounting saidcarrier member for vertical movement relative to said trough member suchthat said printing cylinder may be subjected to the action of saidetchants, raising and lowering mechanisms operatively connected to saidcarrier member for effecting vertical movement thereof relative to saidtrough member, means openatively engaging and mounting said troughmember for lateral movement relative to said carrier member such thatsaid printing cylinder may be subjected in succession to the action ofsaid first and second etchants, shifting mechanisms operativelyconnected to said trough member for effecting lateral movement thereofrelative to said carrier member, a wash boom movable into an operativeposition over said trough member, boom-moving mechanisms operativelyconnected to said wash boom for moving the same into said operativeposition, and means for coordinating said raising and loweringmechanisms, said shifting mechanisms and said boom-moving mechanisms.

15. A machine for etching printing cylinders comprising a frame, aunitary trough member mounted on said frame and having side by sidewalls adapted to contain quantities of first and second etchantsrespectively, a carrier member adapted to support a printing cylinderabove said trough member, means operatively engaging and mounting saidcarrier member for vertical movement relative to said trough member suchthat said printing cylinder may be subjected to the action of saidetchants, raising and lowering mechanisms operatively connected to saidcarrier member for effecting vertical movement thereof relative to saidtrough member, means operatively engaging and mounting said troughmember for lateral movement relative to said carrier member such thatsaid printing cylinder may be subjected in succession to the action ofsaid first and second etchants, shitting mechanism operatively connectedto said trough member for efiectin-g lateral movement thereof relativeto said carrier member, means for coordinating said raising and lower-22 ing mechanisms and said shifting mechanisms, and first and secondagitating means in operative relation to said first and second wells foragitating said first and second etchants during the exposure of saidprinting cylinder to the action of said first and second etchants.

16. A machine for etching printing cylinders comprising a frame, aunitary trough member mounted on said frame and having side by sidewells adapted to contain quantities of first and second etchantsrespectively, a carrier member adapted to support a printing cylinderabove said trough member, turning means adapted to operatively engagesaid printing cylinder for rotating said printing cylinder on its axis,means operatively connected to said turning means for periodicallyreversing the direction of turning of said printing cylinder, meansoperatively engaging and mounting said carrier member for verticalmovement relative to said trough member such that said printing cylindermay be subjected to the action of said etchants, raising and loweringmechanisms operiatively connected to said carrier member for effectingvertical movement thereof relative to said trough member, means operatively engaging and mounting said trough member for lateral movementrelative to said carrier member such that said printing cylinder may besubjected in succession to the action of said first and second etchants,shifting mechanisms operatively connected to said trough member 'forelfecting lateral movement thereof relative to said carrier member, andmeans for coordinating said rasing and lowering mechanisms and saidshifting mechanisms.

References Cited in the file of this patent UNITED STATES PATENTS1,371,338 Andresen Mar. 15, 1921 1,555,105 Dausman Sept. 29, 19252,566,142 Powers Aug. 28, 1951 2,645,236 Fisher July 14, 1953 2,803,078Coughlin- Aug. 20, 1957 2,828,192 Langsfeld Mar. 25, 1958 2,852,072Ailtery Sept. 16, 1958 2,865,125 Langsfeld Dec. 23, 1958 2,881,059Spencer Apr. 7, 1959 2,897,891 Nergaard Aug. 4, 1959 FOREIGN PATENTS2,770 Great Britain 1911 315,260 Great Britain Apr. 60, 1929 454,596Germany Feb. 17, 1927 466,707 Germany J an. 15, 1927

2. A MACHINE FOR ETCHING PRINTING CYLINDERS COMPRISING A FRAME, AUNITARY TROUGH MEMBER MOUNTED ON SAID FRAME AND HAVING SIDE BY SIDEWELLS ADAPTED TO CONTAIN QUANTITIES OF FIRST AND SECOND ETCHANTSRESPECTIVELY, A CARRIER MEMBER ADAPTED TO SUPPORT A PRINTING CYLINDERABOVE SAID TROUGH MEMBER, MEANS OPERATIVELY ENGAGING AND MOUNTING SAIDCARRIER MEMBER FOR VERTICAL MOVEMENT RELATIVE TO SAID TROUGH MEMBER SUCHTHAT SAID PRINTING CYLINDER MAY BE SUBJECTED TO THE ACTION OF SAIDETCHANTS, RAISING AND LOWERING MECHANISMS OPERATIVELY CONNECTED TO SAIDCARRIER MEMBER FOR EFFECTING VERTICAL MOVEMENT THEREOF RELATIVE TO SAIDTROUGH MEMBER, MEANS OPERATIVELY ENGAGING AND MOUNTING SAID TROUGHMEMBER FOR LATERAL MOVEMENT RELATIVE TO SAID CARRIER MEMBER SUCH THATSAID PRINTING CYLINDER MAY BE SUBJECTED IN SUCCESSION TO THE ACTION OFSAID FIRST AND SECOND ETCHANTS, SHIFTING MECHANISMS OPERATIVELYCONNECTED TO SAID TROUGH MEMBER FOR EFFECTING LATERAL MOVEMENT THEREOFRELATIVE TO SAID CARRIER MEMBER, AND MEANS FOR COORDINATING SAID RAISINGAND LOWERING MECHANISMS AND SAID SHIFTING MECHANISMS.